COMPUTING TOPIC COMPONENT ONE parts of a computer system Flashcards

1
Q

What is the purpose of a computer?

A

to take data, process it, then output it

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2
Q

Why were computers built?

A

to help process data and complete tasks more efficiently than humans

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3
Q

What does a computer system consist of?

A

hardware and software that work together to process tasks

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4
Q

What is hardware?

A

the physical stuff that makes up your computer

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5
Q

What is software?

A

the programs or applications that a computer system runs

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6
Q

What are external pieces of hardware called?

A

peripherals

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7
Q

How are there many types of computers sytems?

A
  • range from small (calculators) to big (supercomputers used by banks)
  • general purpose (PCs) to dedicated systems (controlling traffic lights)
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8
Q

What are emedded systems?

A

computers built into other devices e.g. microwaves and TVs, they are usually dedicated systems

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9
Q

What do embedded systems do?

A
  • often used as control machinery, they monitor and control the other parts to produce a desired result
  • as they’re dedicated to a single task, they are usually easier to design, cheaper to produce and more efficient at their job than a general purpose computer
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10
Q

What does the power supply do?

A

provide power to motherboard, optical and hard drives, and other hardware

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11
Q

What does a case cooling fan do?

A

extracts hot air from inside the computer case

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12
Q

What does the CPU heat sink and cooling fan do?

A

keeps the CPU at a steady temperature

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13
Q

What does the CPU do?

A

processes all the data and instructions that make a computer work

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14
Q

What does the Hard Disk Drive do?

A

provide internal secondary storage

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15
Q

What does the motherboard do?

A

the main circuit board in the computer where all the hardware is connected

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16
Q

What does the optical drive do?

A

the reading/writing of optical disks

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17
Q

What does the processing power of the CPU depend on?

A
  • clock speed
  • number of cores
  • cache size
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18
Q

What does the CPU architecture describe?

A
  • the main components of the CPU
  • how they interact with each other
  • how they interact with other parts of the system
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19
Q

What are the three main parts of the CPU?

A
  • the control unit
  • the arithmetic logic unit
  • the cache
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20
Q

What does the control unit do?

A
  • in overall control of the CPU, main job is to execute program instructions following the fetch-decode-execute cycle
  • controls the flow of data inside and outside the CPU
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21
Q

What does the arithmetic logic unit do?

A
  • does all the calculations
  • simple addition, subtraction, multiplication, division and compares the size of numbers
  • performs logic operations such as AND, OR, NOT
  • performs binary shifts
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22
Q

What does the cache do?

A
  • very fast memory in CPU, slower than registers but faster than RAM
  • stores regularly used data so that the CPU can access it quicker
  • when the CPU requests data, it will first check the cache to see if it’s there, if not then it will check the RAM
  • caches have a very low capacity and are expensive compared to the RAM
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23
Q

What are the different levels of cache memory?

A
  • L1, L2, L3

- L1 is quickest but holds the least, L2 is slower but holds more, L3 is slowest but holds the most

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24
Q

What are the CPU registers?

A
  • temporarily hold tiny bits of data needed by the CPU

- they are super quick to read/write to, much quicker than any form of memory

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25
Q

What does the Von Neumann architecture?

A

describes a system where the CPU runs programs stored in the memory

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26
Q

What do programs consist of in the Von Neumann architecture?

A

instructions and data which are stored in the memory addresses

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27
Q

What register does the control unit contain?

A

program counter

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28
Q

What register does the arithmetic logic unit contain?

A

accumulator

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29
Q

What other registers are in the CPU?

A
  • memory address register

- memory data register

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30
Q

What is the function of the program counter?

A

holds the memory address of the instruction for each cycle

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31
Q

What is the function of the memory address register?

A
  • holds any memory address about to be used by the CPU

- the address might point to data or an instruction

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32
Q

What is the function of the memory data register?

A
  • holds the actual data or instruction

- may have been fetched from the memory or waiting to be written to the memory

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33
Q

What is the function of the accumulator?

A

stores intermediate results of calculations in the ALU

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34
Q

What does the memory hold in Von Neumann architecture?

A

holds the program instructions and the program data

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35
Q

What is one feature of the Von Neumann architecture?

A

only uses one memory for both data and instructions

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36
Q

What happens in the fetch instruction?

A
  • copy memory address from the program counter to the MAR
  • copy the instruction stored in the MAR address to the MDR
  • increment the program counter to point to the address of the next instruction ready for the next cycle
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37
Q

What happens in the decode instruction?

A
  • instruction in the MDR is decoded by the control unit

- control unit may then prepare for next step e.g. loading values into MAR or MDR

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38
Q

What happens in the execute instruction?

A
  • the instruction is performed
  • this could be: load data from memory, write data to memory, do a calculation or logic operation using ALU, change the address in the program counter, or halt the program
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39
Q

What is the difference between the program counter and the MAR?

A
  • program counter starts off each cycle by pointing to the instruction
  • MAR has to process all memory address for both data and instructions which means its value might change several times each cycle
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40
Q

What does the memory contain?

A

all the instructions that the CPU follows

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41
Q

What is the RAM used as?

A

the main memory in the computer

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42
Q

What is the main memory?

A

where all data, files and programs are stored while they’re being used

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43
Q

How is RAM used?

A
  • when the computer boots up, the OS is copied from secondary storage to the RAM
  • when applications, documents or files are opened, they are copied from secondary storage to RAM and stay in the RAM until they are closed
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44
Q

What is the speed of RAM like?

A

slower than the CPU cache but faster than secondary storage

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45
Q

How is virtual memory created?

A
  • computers have a limited amount of RAM, as applications are opened, the RAM fills with data
  • when RAM is full, computer needs somewhere else to put application data
  • it moves data that hasn’t been used recently to a location on secondary storage known as virtual memory
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46
Q

When is virtual memory needed?

A

if there are too many applications open, or there is a memory-intensive application, or both

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47
Q

How are transfer rates slower when using virtual memory?

A
  • if the CPU needs to read data from virtual memory, it must transfer the data back to RAM
  • this is slow as data transfer rates are slower on secondary storage than on RAM
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48
Q

How does using virtual memory make a computer slow to respond?

A
  • when switching between applications, while data for one application is swapped for another in virtual memory
  • when using a memory-intensive program, due to data constantly moving between virtual memory and RAM just to keep the program running
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49
Q

What is the BIOS?

A

a type of firmware, hardware-specific software built into a device

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50
Q

How is ROM found in a computer?

A

a small factory-made chip built into the motherboards

51
Q

What does ROM on a computer contain?

A
  • all the instructions the computer needs to properly boot up
  • these instructions are known as the BIOS
52
Q

What does the CPU do with ROM when booted up?

A
  • reads instructions from ROM
  • tells CPU to perform self-checks and set up the computer
  • e.g. test the memory is working OK, see what hardware is present and copy the operating system onto the RAM
53
Q

How can the BIOS be updated

A

you can flash the BIOS on a ROM chip

54
Q

What type of memory do ROM chips use?

A

flash memory

55
Q

What is flash memory?

A
  • very common type of non-volatile memory that stores data in electrical circuits by trapping electrons
  • used in SD cards, USB sticks, SSD
56
Q

How does clock speed affect CPU performance?

A
  • higher the clock speed, the higher the number of instructions per second
  • is possible to overlock, but can make CPUs overheat which can cause crashes or damage to the system, high performance cooling solutions are usually needed
57
Q

How does the number of cores affect CPU performance?

A
  • each core in a CPU processes data independently
  • more number of cores, the more instructions it can carry out at once so the faster it can process a bunch of data
  • most PCs and smartphones have 4 or more cores
58
Q

Why doesn’t doubling the number of cores double the performance of a CPU?

A
  • software needs to be designed to be able to use multi-core processing
  • not all processing tasks split evenly between the cores, some steps will depend on others meaning some cores may be waiting for another core to catch up
59
Q

How does cache size affect CPU performance?

A

a large cache means that the CPU faster access to more data it needs to process

60
Q

How does RAM affect computer performance?

A
  • too little RAM means that the computer may have to rely on virtual memory
  • more the RAM, the more applications or more memory-intensive programs the computer can run making the system smoother
61
Q

What are GPUs?

A
  • specialised circuits for handling graphics and image processing
  • relieve the processing load on CPUSs, freeing it do other things
62
Q

How do GPUs work?

A
  • computers have a basic GPU integrated into the motherboard or CPU, for better graphics performance a dedicated GPU is often used
  • using high-end graphics cards can greatly improve performance in graphics-intensive applications
63
Q

What is tertiary storage?

A
  • used for long-term data storage

- mainly used for archives and back-ups of massive amounts of data

64
Q

What is secondary storage hold?

A

all data when not in use

65
Q

How does a HDD work?

A
  • made up of a stack of magnetised metal disks spinning at a rate between 5400 and 15000 rpm
  • data is stored magnetically on small areas called sectors on circular tracks
  • read/write heads on a moving arm are used to access sectors on the disks
66
Q

Why are HDDs reliable?

A
  • portable HDDs are popular for backing up and transporting large amounts of data
  • despite moving parts, HDDs are long-lasting and reliable, although data could be affected after a sudden impact such as a drop
67
Q

How do SSDs work?

A

-internal storage with no moving parts, most of them use flash memory

68
Q

What is an advantage for SSDs when using a computer?

A
  • using SSDs can give quicker times for booting up the system and opening programs and files compared to a HDD
  • like HDDS, portable SSDs can be used to back up and transport large amounts of data
69
Q

What are some other types of flash storage?

A
  • pen drives and memory cards
  • much slower than SSDs and have a much shorter read/write life
  • used to expand the storage capacity of small devices such as cameras or smartphones
  • they have a very large storage capacity in relation to their tiny size
70
Q

What are some advantages of HDDs?

A
  • cheaper
  • higher capacity
  • have a longer read/write life than SSDs, SSDs can only be written a certain number of times before they start to deteriorate
71
Q

What are some advantages of SSDs?

A
  • faster
  • don’t need defragmenting
  • more shock-proof
  • HDDs make some noise, SSDs are silent
72
Q

How much data can optical discs store?

A
  • CDs can store around 700MB
  • DVDs can hold around 4.7GB
  • Blu-Rays can hold around 25GB
73
Q

What are the three forms that optical disks can come in?

A
  • read only: CD-ROM, DVD-ROM, BR-ROM
  • write-once: CD-R, DVD-R, BR-R
  • rewritable: CD-RW, DVD-RW, BR-RW
74
Q

How does an optical disc work?

A
  • data is stored as microscopic indentations on the surface of the disc
  • data is read by shining a laser beam on the surface and detecting changes in position of reflected beam
75
Q

Why are optical discs declining in usage?

A
  • as Internet speeds, new streaming and downloading servies have eliminated the need for optical discs
  • modern devices such as phones, tablets, and new computers don’t have optical drives
  • DVD-Rs and DVD-RWs used to be popular for backing up data but can’t compete with flash storage due to low capacity per disc, very slow read/write speeds, and poor reliability of RW discs
76
Q

What are some advantages of optical discs?

A
  • very cheap
  • portable
  • won’t be damaged by water or shocks (although easily scratched)
77
Q

What are advantages of magnetic tape?

A
  • greater storage capacity than HDDs

- extremely low cost per GB

78
Q

What are magnetic tapes used for?

A
  • large organisations in archive libraries who store large amounts of data
  • businesses who need to do large frequent back-ups
79
Q

How do magnetic tapes work?

A
  • come in plastic cassettes containing reels of tape

- cassettes require a special tape drive for reading/writing

80
Q

How is magnetic tape read/written to and from?

A
  • read/writing takes place from beginning of tape until end unless computer stops it
  • this means it has a slow read/write speed when finding specific data but a fast read/write speed when it’s in the correct place
81
Q

Rank of average read/write speed from slowest to fastest?

A
  • optical disc
  • memory card
  • magnetic tape
  • HDD
  • SDD
82
Q

Rank of average cost per GB from cheapest to priciest?

A
  • magnetic tape
  • optical disc
  • HDD
  • memory card
  • SSD
83
Q

Rank of average capacity from lowest to highest?

A
  • optical disc
  • memory card
  • SSD
  • HDD
  • magnetic tape
84
Q

What is system software?

A
  • software designed to maintain and run a computer system

- the most important one is the OS

85
Q

What are the main functions of the OS? (6)

A
  • communicate with internal and external hardware via the device drivers
  • allowing the user to interact with the computer via a user interface
  • provide a platform for the different applications to run on
  • allow the computer to multi-task by controlling memory resources and CPU
  • deal with file management and disk management
  • manage the security of the system e.g. through user accounts
86
Q

How does the OS use device drivers?

A
  • to allow communication with the internal hardware and peripherals connected
  • every piece of hardware connected to the computer system requires a device driver which acts as a ‘translator’ for the signals between the OS and the hardware
87
Q

What will happen with device drivers when the computer is booted up?

A
  • when the computer is booted up, the OS will choose the correct device drivers for the hardware that it detects
  • if new hardware is detected, the system will install new device drivers for that hardware
88
Q

How are device drivers updated?

A
  • device manufacturers may release updates to the device drive in order to fix bugs, improve hardware or add features
  • updates may be installed automatically by the OS or manually by the user
89
Q

What are GUIs?

A
  • most common type of user interface

- designed to be easy for everyday users by making them visual, interactive and intuitive

90
Q

How are GUI systems optimised?

A
  • optimised for specific input methods
  • in the past, GUIs have been WIMP-based (windows,icon,menus,pointers)
  • Android and iOS created for touchscreen devices using finger gestures such as pinching and swiping in place of a mouse
91
Q

What is a command-line interface?

A
  • text-based interface
  • user enters specific commands to complete tasks
  • command-line interfaces are less resource-heavy than GUIs
92
Q

How are command-line interfaces suitable?

A
  • aren’t suitable for everyday users
  • for advanced users, they can be far more efficient and powerful than GUIs
  • can be used to automate programs using scripts
93
Q

How do OSs provide a platform to run applications?

A

by configuring hardware so they can use it and giving access to the CPU and memory

94
Q

What are OSs that can run multiple applications at the same time called?

A

multi-tasking OSs

95
Q

How does the OS help the CPU carry out multi-tasking efficiently?

A
  • when an application is opened, the OS moves the application to the memory in addition to other parts if they are needed
  • the OS determines if an application has been used recently, if not then it may be removed from memory
  • to run multiple applications, the OS needs to make sure applications don’t override or interfere with each other
  • only one application is processed by the CPU at a time, so the other processes must wait
  • the OS divides CPU time between open applications and may prioritise certain processes so instructions can be executed in most efficient order
  • when required, OS organises data movement to and from virtual memory
96
Q

How does the OS ensure that applications don’t interfere or override with each other?

A

a memory manager allocates certain applications certain memory addresses, to make sure their processes are placed in certain locations

97
Q

How do files work on a computer?

A
  • computers store data as files
  • images, music, videos and spreadsheets are all just collections of data
  • file extensions tell the computer which software should be used to open the file
98
Q

How is the OS responsible for file management?

A
  • manages data into a hierarchical structure

- deals with movement, editing and deletion of data

99
Q

How does the OS manage files on the hard disk?

A
  • splits the physical disk into storage sectors, decides which sectors to write data to and keeps track of free space on the disk
  • ideally, the data for a single file would be stored in adjacent sectors but this isn’t always possible
100
Q

How can OS use utility software to manage files?

A
  • file compression can reduce the size of individual files
  • encryption can secure the content of files
  • defragmentation can help organise and manage the hard disk by moving all the free space together
101
Q

What is a single-user OS?

A
  • allow only one user to access the computer at once
  • most modern OSs (macOS, Windows 10) are like this even if they allow multiple user accounts or are connected to a network
102
Q

What is a multi-user OS?

A
  • allow several users to access the computer at the same time
  • often used on mainframes (huge supercomputers) and allow multiple users simultaneous access
  • e.g. ATMs allow thousands of people to access a bank’s mainframe at the same time
103
Q

How are OSs responsible for user account control?

A
  • user accounts allow users to access specific data or resources on a computer system
  • on most desktop OSs, each user has access to their own personal desktop and files but no one else’s
104
Q

How do OSs use anti-theft measures for user accounts?

A
  • may have anti-theft measures to prevent other users accessing locked devices or accounts to steal information
  • user accounts may be password or pin-protected
  • some deices also require user to draw a specific pattern, or have fingerprint or retina scanners
105
Q

What is utility system software?

A
  • helps to maintain or configure a computer

- much useful utility software already installed on OS but more may be installed by user to perform additional tasks

106
Q

How does fragmentation occur on a HDD?

A
  • as files are moved, deleted or change size, lots of small gaps begin to appear on the disk
  • when writing files to disk, OS splits files into smaller chunks to fill gaps on disk
  • over time, the disk becomes more fragmented
  • this makes reading/writing files slower as the read/write head has to move back and forth across the disk
107
Q

What does defragmentation software do?

A
  • reorganises data so that fragmented files are back together
  • also organises files so that all free space is collected together which prevents further fragmentation
108
Q

Why don’t SSDs need defragmentation?

A
  • as SSDs have flash storage with no moving parts, fragmentation isn’t a problem as they can access data just as quickly no matter how it’s stored
  • because SSDs have a limited amount of read/writes, defragmentation can shorten their lifespan
109
Q

What is a backup?

A
  • a copy of a computer system’s files and settings stored externally
  • this means data can be recovered in the event of data loss
110
Q

What is a backup utility?

A

software with facilities such as scheduling of regular back ups, creating rescue disks, disk images and options for full or incremental backups

111
Q

What is a full backup?

A
  • where a backup is made of every file from the system
  • often take a large storage space
  • take longer to backup
  • however, are quicker to restore from
112
Q

What is an incremental backup?

A
  • where only files that have been created or edited since the last back up are copied
  • use less storage space
  • take much quicker to backup
  • take much longer to restore, need to restore last full backup plus every incremental back up since then
113
Q

What is compression software?

A
  • reduces size of files so they take up less disk space
  • used frequently on the Internet so that they take less time to download
  • common file extensions include .zip and .rar
  • files need to be extracted before they can be used
114
Q

What is encryption software?

A
  • encrypts data so that third-parties can’t access it

- encrypted data can be decrypted using a special key

115
Q

What is open source software?

A
  • software where the source code is made freely available
  • users may legally modify the source code to create their own spin-off software which can be shared under the same license and terms of the original software
116
Q

What are some examples of open source software?

A
  • Mozilla Firefox
  • GIMP
  • VLC media player
117
Q

What is Linux?

A
  • hugely successful open source OS released in 1991

- hundreds of Linux-based OSs have been developed and shared over the years such as Ubuntu and Android

118
Q

What does popular open source software have?

A
  • supported by a strong online community
  • users actively help to improve software, anyone can play with source code and suggest bug fixes and improvements to original developers
119
Q

What are some advantages of open source software?

A
  • usually free
  • made for the greater good, not profit
  • software can be adapted by users to fit their needs
  • wide pool of collaborators can be more creative and inventive than programmers of one company
  • usually secure and reliable, any problems are quickly fixed by community
120
Q

What are some disadvantages of open source software?

A
  • small projects may not get regular updates, so could be buggy or have unpatched security holes
  • may be limited user documentation
  • no warranties if something goes wrong
  • no customer support
  • companies making custom software based off open source software may not want competitors to see software code but are left with no choice
121
Q

What is proprietary software?

A
  • usually paid for
  • only the compiled code is released and the source code is kept secret
  • proprietary software licenses may restrict the modifying, copying and redistribution of the software
  • businesses tend to use as it has better customer support options
122
Q

What are some advantages of proprietary software?

A
  • comes with warranties, documentation and customer support
  • should be well-tested and reliable as the company’s reputation relies on this
  • fixes and updates come regularly
  • usually cheaper for companies than developing their own custom built software
123
Q

What are some disadvantages of proprietary software?

A
  • can be expensive
  • software may not exactly fit a user’s needs and there’s nothing they can do about it
  • software companies may not maintain older copies after warranties expire, they’ll want people to buy latest product